/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law
 * or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.apache.commons.dbutils;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

/**
 * Creates proxy implementations of JDBC interfaces. This avoids
 * incompatibilities between the JDBC 2 and JDBC 3 interfaces. This class is
 * thread safe.
 * 
 * @see java.lang.reflect.Proxy
 * @see java.lang.reflect.InvocationHandler
 */
@SuppressWarnings("unchecked")
public class ProxyFactory {

	/**
	 * Class[] for CallableStatement interface.
	 */
	private static final Class[]		callableStatementClass	= new Class[] { CallableStatement.class };

	/**
	 * Class[] for Connection interface.
	 */
	private static final Class[]		connectionClass			= new Class[] { Connection.class };

	/**
	 * Class[] for Driver interface.
	 */
	private static final Class[]		driverClass				= new Class[] { Driver.class };

	/**
	 * The Singleton instance of this class.
	 */
	private static final ProxyFactory	instance				= new ProxyFactory();

	/**
	 * Class[] for ResultSetMetaData interface.
	 */
	private static final Class[]		metaClass				= new Class[] { ResultSetMetaData.class };

	/**
	 * Class[] for PreparedStatement interface.
	 */
	private static final Class[]		preparedStatementClass	= new Class[] { PreparedStatement.class };

	/**
	 * Class[] for ResultSet interface.
	 */
	private static final Class[]		resultSetClass			= new Class[] { ResultSet.class };

	/**
	 * Class[] for Statement interface.
	 */
	private static final Class[]		statementClass			= new Class[] { Statement.class };

	/**
	 * Returns the Singleton instance of this class.
	 * 
	 * @return singleton instance
	 */
	public static ProxyFactory instance() {
		return instance;
	}

	/**
	 * Protected constructor for ProxyFactory subclasses to use.
	 */
	protected ProxyFactory() {
		super();
	}

	/**
	 * Creates a new proxy <code>CallableStatement</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied CallableStatement
	 */
	public CallableStatement createCallableStatement(InvocationHandler handler) {
		return (CallableStatement) Proxy.newProxyInstance(handler.getClass().getClassLoader(), callableStatementClass, handler);
	}

	/**
	 * Creates a new proxy <code>Connection</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied Connection
	 */
	public Connection createConnection(InvocationHandler handler) {
		return (Connection) Proxy.newProxyInstance(handler.getClass().getClassLoader(), connectionClass, handler);
	}

	/**
	 * Creates a new proxy <code>Driver</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied Driver
	 */
	public Driver createDriver(InvocationHandler handler) {
		return (Driver) Proxy.newProxyInstance(handler.getClass().getClassLoader(), driverClass, handler);
	}

	/**
	 * Creates a new proxy <code>PreparedStatement</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied PreparedStatement
	 */
	public PreparedStatement createPreparedStatement(InvocationHandler handler) {
		return (PreparedStatement) Proxy.newProxyInstance(handler.getClass().getClassLoader(), preparedStatementClass, handler);
	}

	/**
	 * Creates a new proxy <code>ResultSet</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied ResultSet
	 */
	public ResultSet createResultSet(InvocationHandler handler) {
		return (ResultSet) Proxy.newProxyInstance(handler.getClass().getClassLoader(), resultSetClass, handler);
	}

	/**
	 * Creates a new proxy <code>ResultSetMetaData</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied ResultSetMetaData
	 */
	public ResultSetMetaData createResultSetMetaData(InvocationHandler handler) {
		return (ResultSetMetaData) Proxy.newProxyInstance(handler.getClass().getClassLoader(), metaClass, handler);
	}

	/**
	 * Creates a new proxy <code>Statement</code> object.
	 * 
	 * @param handler
	 *            The handler that intercepts/overrides method calls.
	 * @return proxied Statement
	 */
	public Statement createStatement(InvocationHandler handler) {
		return (Statement) Proxy.newProxyInstance(handler.getClass().getClassLoader(), statementClass, handler);
	}

}
